Erosion control Islands in high bank stream remediation

ABSTRACT

This process will provides an efficient cost effective method for reducing and potentially alleviating high bank erosion without using rip rap stone. The process will utilize a series of geotextile islands and sand bag walls interconnected into energy deflecting, erosion control structures. Each geotextile island is constructed from a water-permeable fabric tube with a diameter up to 45 feet. This fabric may be cut into lengths of approximately five to twelve feet, with one end subsequently folded and secured to become a drop shaped geotextile island. The islands will be placed as a hard point connecting structure with an interlocking sand bag wall.

BACKGROUND

Please note: This is an application that closely resembles PROVISIONAL PATENT #61,181,738 which incorrectly identifies Mr. David Ogden as the inventor. Mr. Ogden agreed to assist Mr. Daily in authoring this application and then singularly paraphrased the method described by Mr. Daily into an application which he submitted, listing himself as the inventor.

Remediation of any situation involving flowing water eroding into a steep or high bank shore line has historically required amortizing the eroded surface and deflecting flows with the placement of material against the bank. Rip rap stone is generally the material of choice, but, because of the high cost of stone placement and continued maintenance, many unacceptable substitutes are utilized including, but not limited to, no action, retaining walls, old vehicles, garbage, asphalt and concrete.

The following method is an economical, environmentally sound approach to improving the transfer of water flows from high bank erosion areas utilizing readily available materials.

BRIEF SUMMARY

This method will employ construction of hard points to deflect water currents away from eroded banks. These hard point, cone shaped islands will be created by forming and filling geotextile tubes in preselected locations. Each island will then be tied together using a sand bag barrier wall impregnated with native plant materials. Both the islands and walls will further train water flow and deflect erosive energy to mid stream while providing a stable secure plant median. High energy water flowing through this plant material will accomplish multiple functions including decreasing erosive energy against the bank and increased silt deposition on the landward side which rebuilds the bank and anchors the islands and walls in place in the predetermined location. The islands and sandbag walls will act as the temporary (1 to 3 years) foundation bed for the native grasses shrubs, and trees. By the time the geotextile (geobag) islands and sandbags biodegrade, there should be a living wall of native plant materials to remain in place.

BRIEF DESCRIPTION OF ATTACHED FIGURES

FIG. 1—Plan view of actual river bank and resulting high bank erosion.

FIG. 2—Plan view of river bank conditions with erosion control islands and sandbags containing native plant materials.

FIG. 3—plan view of a single unit of island, wall erosion control.

FIG. 4—Representation depicting cross sections of geobag islands and connecting sandbag barriers.

FIG. 5—Representation depicting detail of modified concrete bucket used to fill geobags with soil, sand, clay or any other suitable fill material.

FIG. 6—Representation depicting detail of geobag island filling and placement using the modified concrete bucket filled with soil, sand, clay or any other suitable fill material.

FIG. 7—Representation depicting detail of living sand bag components of barrier walls filled with native grasses and plant seeds and soil, sand, clay or any other suitable fill material.

DETAILED DESCRIPTION

01) The purpose and need of this method is to provide an economic, environmentally sound alternative to address the conditions that result in undesirable high bank erosion.

02) Living erosion control is ineffective in these areas because of the unstable and unfertile soil properties, extreme slopes and the erosive effects of high energy flows on roots from these areas. Those areas planted in an effort to reduce erosion generally fail as a result of the plants stuffing from the slope or washing away during medium and high velocity events.

03) The islands will be constructed in place by suspending commercially available geotextile tubes on end and inverting the outside edge of this tube inward toward the middle. The inverted edges will be gathered toward the center of the bag and then secured to form a drop shaped bag. The geobag will then be filled by pumping a variety of materials in to the bottom and filling toward the top.

04) The sand bag walls will be constructed from commercially available sand bags filled with native plant seeds, sand, soils, and or potting material folded closed on the open end to form a pliable pillow. Each pillow will be placed in such a manner as to create a multi-level wall with a shingle effect to address high velocity flows.

05) The islands and walls will be sized and placed according to flow rates and patterns. The addition of the geobag islands as hard points in conjunction with the sand bag walls will realign flow patterns away from the high bank areas.

06) Plant selection (numbers, variety, and sizes) will be selected according to water velocities, bank slope and heights.

07) Construction activities will remain above and out of the waterway. A mobile crane or trac hoe will be positioned on a section of the riverbank selected for remediation. The terminus of the crane's hoisting cable will be fitted with a modified concrete bucket. The concrete bucket will be modified with the addition of a spring clamp device to hold the geotextile bag open for filling.

08) Materials used to construct the geobag islands may be either delivered from a remote location and stockpiled at the remediation site or excavated from nearby locations. A skid-steer or similar loader will be employed at the shore location to load soils into the modified concrete bucket or into a hopper for delivery by a modified concrete pump with flexible hose.

09) A shore worker will attach an empty geotextile tube sealed at the bottom to the lower skirt of the modified concrete bucket using spring clamps. A trac hoe or crane will lower the empty geobag to an elevation of approximately four feet above ground level at the desired location in the stream.

10) The trac hoe or crane will then suspend the empty geobag at the base of the eroded bank beneath the mobile soil hopper at an elevation so that the base of the soil bag is in contact with the ground and the sides of the soil bag remain vertical.

11) The spring clamp on the modified concrete bucket maintains orientation of the bag so that the bag fills properly and prevents the bag from folding upon itself or collapsing.

12) Once filled to the desired level and appropriate drop shape, the geobag island is disconnected from the modified concrete bucket and sealed shut. The modified concrete bucket is returned to be restaged for additional islands if necessary.

13) The sand bag wall will be constructed off site in the following manner:

Standard commercially available sand bags will be filled with native plant seeds, sand, soils, and or potting material folded closed on the open end to form a pliable pillow (a patent on this design and application will be submitted at a later date). Each bag will be placed in such a fashion as to create a multiple level living wall and silt fence. The wall will be constructed along predetermined lines to modify water currents away from eroded areas and into a less erosive path.

14) Plants are inserted within the geobag islands and, as deemed necessary, shoreward of the sand bag walls.

15) These operations are repeated until geotextile islands have been installed at all desired locations within the reach of the crane or trac hoe. The mobile crane is then repositioned to another point and the process is repeated until enough hard points are created to accomplish a change in flow patterns.

16) Plant roots may be expected to propagate through the geotextile material and nylon sand bag covers. The location of the islands and attached sand bag walls are designed in such a manner that sediments will collect on the landward side of both. This collected silt material combined with subsequent plant growth will fill in and provide additional protection to the eroded bank.

17) With time, the islands and walls will provide hard point structures resulting in a natural reconstruction and restoration of previously eroded high bank stream areas. 

1. Unique features of this method of high bank erosion control include: The use of geobags created by sealing the bottom of a geotextile material tube and standing it on end to create a drop shaped structure instead of the normally utilized tube structure running lengthwise with the bank. The use of sand bags filled with a growing medium and seeds to create a living wall. The modification of a concrete bucket to include spring clamps to hold the geobag islands upright during filling. The use of the combined island and wall structures as hard points and guide structures to divert high flow, high velocity waters from high bank areas being eroded. 